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Longitudinal Measurements of Oxygen Consumption in Growing Infants during the First Weeks after Birth: Old Data Revisited.
MedLine Citation:
PMID:  23364102     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Background: In a study conducted in 1966-1969, longitudinal measurements were made of the metabolic rate in growing infants. Statistical methods for analyzing longitudinal data weren't readily accessible at that time. Objectives: To measure minimal rates of oxygen consumption (V·O(2), ml/min) in growing infants during the first postnatal weeks and to determine the relationships between postnatal increases in V·O(2), body size and postnatal age. Methods: We studied 61 infants of any birth weight or gestational age, including 19 of very low birth weight. The infants, nursed in incubators, were clinically well and without need of oxygen supplementation or respiratory assistance. Serial measures of V·O(2) using a closed-circuit method were obtained at approximately weekly intervals. V·O(2) was measured under thermoneutral conditions with the infant asleep or resting quietly. Data were analyzed using mixed-effects models. Results: During early postnatal growth, V·O(2) rises as surface area (m(2))(1.94) (standard error, SE 0.054) or body weight (kg)(1.24) (SE 0.033). Multivariate analyses show statistically significant effects of both size and age. Reference intervals (RIs) for V·O(2) for fixed values of body weight and postnatal age are presented. As V·O(2) rises with increasing size and age, there is an increase in the skin-operative environmental temperature gradient (T skin-op) required for heat loss. Required T skin-op can be predicted from surface area and heat loss (heat production minus heat storage). Conclusions: Generation of RIs for minimal rates of V·O(2) in growing infants from the 1960s was enabled by application of mixed-effects statistical models for analyses of longitudinal data. Results apply to the precaffeine era of neonatal care.
Authors:
J C Sinclair; K Thorlund; S D Walter
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-23
Journal Detail:
Title:  Neonatology     Volume:  103     ISSN:  1661-7819     ISO Abbreviation:  Neonatology     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-31     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101286577     Medline TA:  Neonatology     Country:  -    
Other Details:
Languages:  ENG     Pagination:  223-231     Citation Subset:  -    
Copyright Information:
Copyright © 2013 S. Karger AG, Basel.
Affiliation:
Department of Pediatrics, McMaster University, Hamilton, Ont., Canada.
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